What are the the best Error Message Icons to use for each type of error in .NET? best practices

Question

I'm currently working on a project in .net... I have handled error messages with user friendly instructions, however I'm trying to determine the best error message icons to use. I previously just left it blank but I think icons are more helpful.

Depending on the severity of an error message, what is the recommended practice of displaying the MessageBox.Icon and in which situations should the following be applied?

MessageBoxIcon.Asterisk
MessageBoxIcon.Error
MessageBoxIcon.Exclamation
MessageBoxIcon.Hand
MessageBoxIcon.Information
MessageBoxIcon.None
MessageBoxIcon.Question
MessageBoxIcon.Stop
MessageBoxIcon.Warning

E.g. From the options above what would you use, in a messagebox where...

• A file is not found
• A critical failure occurred
• A non critical failure occurred
• An unexpected value was returned
• An invalid value was entered
• failed to run something
• Or other common exceptions that users may encounter?

Some of these may seem obvious, but please say them anyway for everyone to benefit.

Answer 1

Note to start: There are only 4 different images. Error, Hand and Stop are the same image (white X on red circle.) Question is unique, but Microsoft recommends against its use. Exclamation and Warning are the same image (black exclamation point on yellow triangle.) Asterisk and Information are the same image (lowercase "i" in a circle.) This StackOverflow question explains it well.

Your Examples

• A file is not found: Error. This is what Windows uses when Run cannot find a file.

• A critical failure occurred: Error. This is also commonly used for critical failures in Windows.

• A non critical failure occurred: This varies depending on the specific program and failure, but I would recommend Warning. It indicates the problem is serious (it is a failure after all), but not to the degree of the Error icon.
• An unexpected value was returned: This also varies, but you should use a symbol that indicates the severity of the problem this causes. Will the process continue relatively unaffected? Does the user need to completely re-enter all of their information? If it's minor, omit the icon or use Information.
• An invalid value was entered: See unexpected value returned.
• Failed to run something: Warning. This is what Windows uses for Windows Installer packages.

Summary/TL;DR

The icon should indicate the severity of the problem, with Error being the most severe, Warning being medium severity, and Information or no icon being the least severe.

Answer 2

Microsoft Developer network are very detailed over when and why to use these different icons:

The standard error, warning, information, and question mark icons.

The standard icons have these meanings:

• Error icon. The user interface (UI) is presenting an error or problem that has occurred.
• Warning icon. The UI is presenting a condition that might cause a problem in the future.
• Information icon. The UI is presenting useful information.
• Question mark icon. The UI indicates a Help entry point.

Reference: Standard Icons

Translating this to your case, I would use the following icons:

• Error: A file is not found
• Error: A critical failure occurred
• Warning: A non critical failure occurred
• Error: An unexpected value was returned
• Error: An invalid value was entered
• Error: failed to run something
• Error: Or other common exceptions that users may encounter?